1. Field of The Invention
The present invention relates to controllers for rotatable shafts used in internal combustion engines of motor vehicles. More particularly, the present invention relates to a one-way clutch which allows rotation of a shaft in either direction.
2. Description of The Related Art
Internal combustion engines use a cam shaft which is arranged to controllably open and close the intake and exhaust valves and operate the fuel injector of the engine. The timings for the valving events frequently are fixed for the entire operating conditions of the engine. The opening and closing of the intake and exhaust valves is timed to provide an optimum performance efficiency of the engine during normal cruising speeds for the motor vehicle. However, when the motor vehicle is driven at low speeds, engine performance suffers. Designs of cam shafts that control the intake and exhaust valves at fixed intervals compromise the mutually conflicting requirements of light load and heavy load operating conditions for the engine. Either the requirements of the light load or those of the heavy load operations of the engine are sacrificed.
To resolve these problems, variable valve timing cam shafts have been developed. Variable valve timing cam shafts use a drive mechanism that advances or retards the valving events to improve the overall efficiency and performance of the engine. The opening and closing timings of the intake and exhaust valves can be varied in relation to preselected operating conditions of the engine, such as the output speed of the engine or the vacuum developed in the intake manifold of the engine. Variable valve timing cam shafts improve the engine performance, efficiency, and fuel economy, and also reduce toxic exhaust emissions from the engine.
Numerous patents disclose variable valve timing devices. In Miokovic, U.S. Pat. No. 3,945,221 a coupling device includes a sliding member slidably axially mounted on a first driving shaft. The sliding member slides axially to vary the angular timing of a second separately driven shaft in relation to the first driving shaft. This varies the timing of the engine. In Hisserich, U.S. Pat. No. 3,897,760 varying the valve timing of the intake and exhaust valves is performed by varying the distance between the cam shaft axis and valve lifters which control the portion of the cam shaft revolution during which the cam lobes contact the lifters.
Many patents also disclose mechanical-type clutch systems. In Dossier U.S. Pat. No. 3,861,506, friction-free wheels are provided with a locking reversal device. This system allows rotation in both clockwise and counterclockwise directions. In Kudlacek, U.S. Pat. No. 4,057,220 a ratchet type operator using a spring-loaded arm permits unidirectional rotation of a winch shaft. Other patents such as Carlin, U.S. Pat. No. 4,586,329; Acre, U.S. Pat. No. 4,007,815; and Kinsman, U.S. Pat. No. 1,980,686 are representative of a body of art which discloses releasable locks and antirotation devices for shafts which prevent the shafts either from rotating or from translating. All of these patents disclose mechanisms that either hold a shaft stationary or allow it to move. They do not control the direction of rotation of a shaft. Nor do any devices disclose a system wherein the shaft positions itself without external devices.